The manufacture of reverse loop sliver knit fabric using a circular sliver knitting machine for producing a pile fabric is well known in the art. For example, Schaab et al. in U.S. Pat. Nos. 4,244,198 and 4,245,487 and U.S. Pat. No. 5,431,029 to Kuhrau et al. which have been assigned to the applicant of the present invention each disclose a method and apparatus for making reverse loop sliver knit fabric which uses an air nozzle positioned radially inward from the needles and sinkers. The purpose of the air nozzle is to turn the free ends of the sliver, previously knitted into the base fabric during the first pass of the needles, over the sinkers so that the remaining free ends, assuming that they are of sufficient length, will be knitted a second time or interlaced into the fabric. The result is that the length of the free ends remaining after the second pass is shortened and as a consequence, the pile will be shorter, therefore, less waste will occur as result of shearing. The Kuhrau et al. patent introduced the ability to use the air nozzle to help the needles capture and retain the free ends of the sliver for purposes of interlacing them into the fabric. As a consequence, the resultant fabric has a uniform length without requiring shearing of a large portion of the pile prior to use.
Prior to the Kuhrau et al. patent, it was necessary to individually calibrate the position of every air nozzle unit relative to the needles individually before the machine was ready to produce a commercially usable fabric. Unfortunately, after each such adjustment, it was necessary to run the machine to determine if the positioning of every air nozzle unit was proper. This approach to calibration resulted in a great deal of down time and wasted materials every time a new fabric and/or pattern was to be knit.
Kuhrau et al. disclosed a circular sliver knitting machine which used an adjustable support ring to carry the air nozzle units. To calibrate a machine to accommodate a change in fabric and/or pattern to be knit required the calibration of only one air nozzle unit. Then all the other air nozzle units were calibrated as to their vertical and rotational position because of their connection to the adjustable support ring.
However, it is still necessary to manually calibrate, by means of the adjustable support ring, one air nozzle unit every time the machine is to knit a different fabric and/or pattern. Because even minor adjustments in the vertical and/or rotational position of the air nozzle units relative to the needles has a dramatic effect on the quality and nature of the fabric, significant time is still required to manually adjust the air nozzle units and some waste of raw materials still occurs.